Embodiments of the present disclosure generally relate to systems and methods for a bi-directional communication link between devices, and more particularly for maintaining bi-directional communication between an implantable medical device and an external device.
An implantable medical device (“IMD”) is a medical device that is configured to be implanted within a patient anatomy and commonly employs one or more leads with electrodes that either receive or deliver voltage, current or other electromagnetic pulses (generally “energy”) from or to an organ or tissue for diagnostic or therapeutic purposes. In general, IMDs include a battery, electronic circuitry, such as a pulse generator and/or a microprocessor that is configured to handle RF communication with an external device as well as control patient therapy. The components of the IMD are hermetically sealed within a metal housing (generally referred to as the “can”).
IMDs are programmed by and transmit data to external devices controlled by physicians and/or the patient. The external devices communicate by forming wireless bi-directional communication links with the IMDs. Recently, the IMD may communicate with the external device using commercial protocols such as Bluetooth Low Energy (BLE), which are compatible with commercial wireless devices such as tablet computers, smartphones, and the like. Commercial protocols include several default security mechanisms, such as a frequency hopping algorithm, which change frequencies of subsequent data packets for predetermined communication intervals. However, many of these security mechanisms are based on publicly available wireless protocol specifications, and are implemented using information exchanged between the devices before or prior to communication being encrypted, thereby allowing information exchanged between the devices to be susceptible to packet analyzers or packet sniffers.
Packet sniffers are programs and/or computer hardware designed to intercept and/or log wireless traffic (e.g., transmission of data packets) over a wireless network to eavesdrop or intrude on communications between two devices (e.g., the IMD and an external device). Packet sniffers may capture one or more data packets and decode the one or more data packets determining values of various fields within the data packet. Further, the packet sniffer can analyze content of the various fields according to the wireless protocol specification.
For example, the frequency hopping algorithm is predefined using a connection request packet that includes information based on a specification of the commercial protocol. The packet sniffer can capture and use the information from the connection request packet to frequency hop concurrently with the IMD and the external devices. Thereby, the packet sniffer may follow the frequency hops between the IMD and the external device acquiring one or more of the transmitted data packets transmitted between the devices. Further, the packet sniffer may reuse or replay captured data packets to interrupt communication with the IMD and/or the external device. Additionally, the packet sniffer may reuse and adjust the captured data packets for “man in the middle” attacks on the IMD and/or the external device. Thus, a need exists for improved methods and systems for securing bi-directional communication between the IMD with the external device.